When a child index exists for id, children lists the
sub-entity boxes that intersect the query region. An empty array means the
root entry matched but no child geometry did (for example a stale coarse
root bbox, or a query box that falls inside the aggregate bounds but not
on any child). Selection and pick paths filter these with
isEffectiveSpatialQueryHit.
Hierarchical spatial-query result.
When a child index exists for id, children lists the sub-entity boxes that intersect the query region. An empty array means the root entry matched but no child geometry did (for example a stale coarse root bbox, or a query box that falls inside the aggregate bounds but not on any child). Selection and pick paths filter these with isEffectiveSpatialQueryHit.